linux-kernel - Re: [PATCH 1/1] vhost: Protect the virtqueue from being cleared whilst still in use

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Date:   Tue, 8 Mar 2022 08:01:32 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     jasowang@...hat.com, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org,
        netdev@...r.kernel.org, stable@...r.kernel.org,
        syzbot+adc3cb32385586bec859@...kaller.appspotmail.com
Subject: Re: [PATCH 1/1] vhost: Protect the virtqueue from being cleared
 whilst still in use

On Mon, 07 Mar 2022, Michael S. Tsirkin wrote:

> On Mon, Mar 07, 2022 at 07:17:57PM +0000, Lee Jones wrote:
> > vhost_vsock_handle_tx_kick() already holds the mutex during its call
> > to vhost_get_vq_desc().  All we have to do here is take the same lock
> > during virtqueue clean-up and we mitigate the reported issues.
> 
> Pls just basically copy the code comment here. this is just confuses.
> 
> > Also WARN() as a precautionary measure.  The purpose of this is to
> > capture possible future race conditions which may pop up over time.
> > 
> > Link: https://syzkaller.appspot.com/bug?extid=279432d30d825e63ba00
> 
> And this is a bug we already fixed, right?

Well, this was the bug I set out to fix.

I didn't know your patch was in flight at the time.

> > Cc: <stable@...r.kernel.org>
> > Reported-by: syzbot+adc3cb32385586bec859@...kaller.appspotmail.com
> 
> not really applicable anymore ...

I can remove these if it helps.

-- 
Lee Jones [李琼斯]
Principal Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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